Cancer is a leading cause of mortality among Americans today. Because standard approaches to treatment of the disease are continually changing, the current patterns of care for cancer patients are not well described. Previous research has found that patterns of care vary markedly for cancer patients. This one-year retrospective evaluation of the patterns of care and outcomes for United States Veterans with colon cancer who received car at VA Hospitals in 1993- 1994 will provide important new data about this cancer. Specifically, we propose to study how diagnostic and treatment strategies for colon cancer vary by age, race, comorbidity, geography and hospital characteristics. This study represents a unique opportunity to merge two existing data sources - a clinically detailed data set for a random sample of 1, 187 Veterans with Colon cancer from 1993-1994 who have been evaluated in the External peer Review Program (EPRP) of the VA and the automated hospital discharge data from the VA, the Patient Treatment Files (PTFs). It has several unique features: 1) the first large scale patterns of care study for colon cancer patients in the VA system, one of the largest health care systems in the country; 2) allows for improvement over previous tumor registry based studies that are limited by not including adjustments for comorbidity or outcomes; 3) includes significant numbers of minorities; 4) is based on a clinically rich data set (the RPRP) merged with the VA automated data set (the PTF); and 5) allows for evaluation of variations in care that are not confounded by different types of health insurance plans.